A common task in various fields is to determine the location of a point on an object relative to another point on the object or another object. In a quality control environment, for example, the relative locations of parts of an item preferably fall within a specified tolerance. In an architectural or building inspection scenario, the foundation of a building is tracked to determine shifts in location over time. In a vehicle repair scenario, a shift in the location of a part determines whether any damage has occurred, and if so, the extent of the damage.
Stereoscopic imaging, or stereoscopy, is used to obtain three-dimensional information about an object based on a pair of two-dimensional images of that object. In general, stereoscopic imaging involves obtaining at least two images of an object, taken from slightly different viewpoints, to determine the three-dimensional information. By obtaining the two stereo images from slightly different perspectives, coordinate locations of desired measurement points identified in both images can be more accurately determined.
Stereoscopic imaging is the basis for photogrammetry, which involves producing stereograms or a pair of stereo images of an object in order to determine geometric properties and/or measurement information about the object. Photogrammetry is used in various fields, such as manufacturing, architectural surveying, building preservation, and archaeology in order to obtain measurement information for an object of interest. When obtaining measurements between particular measurement points on a desired object via photogrammetry, it is generally required that the same measurement points are designated in both images to obtain accurate measurement information.
With the advent of digital image sensors, computer-based image processing techniques have been developed and applied to photogrammetry. The increase in digital image sensor resolution and advancements in computer image-processing have not been efficiently utilized for stereoscopic measurement purposes. A stereoscopic processing system allows easier designation of measurement points in stereo images of an object to obtain more accurate measurements.